Embodiments relate to systems and methods for Wi-Fi like, unlicensed access in digital television (DTV) whitespaces in an enterprise setting.
Many countries are migrating from analog to digital television broadcasts. For example, in the US, this transition happened on Jun. 12, 2009; while in the UK, this transition is slated to happen in a phased manner from 2008 to 2012. In analog transmission, each TV channel uses a 6 MHz slice of bandwidth, but digital transmissions have the ability to pack four “programs” into one 6 MHz channel. Thus, this analog-to-digital transition frees up a substantial amount of television spectrum that was previously used by analog transmissions.
The newly freed up spectrum (along with other slices of unused spectrum in the 50-700 MHz (channels 2-51) television band is known as DTV whitespace (DTV-WS). Signals in the DTV spectrum propagate over long distances and penetrate through obstacles more easily. According to a recent study, 100 to 250 MHz of DTV-WS will be made available depending on the local market. The large amount of spectrum and its superior propagation characteristics make the DTV-WS a highly attractive proposition for wireless broadband deployment and usage.
In November 2008, the FCC ruled that the digital TV whitespaces may be used for unlicensed access by fixed and portable devices. Fixed devices (e.g., IEEE 802.22 base stations) are used for providing last mile internet access in underserved areas, while portable devices may be used to provide short range wireless connectivity for Internet access (e.g., Wi-Fi like access points). Furthermore, the FCC ruled that portable devices could only transmit in channels 21-51 (i.e., 512-698 MHz) and use a transmit power of 40 mW when adjacent to a TV channel in the frequency band and 100 mW on a non-adjacent channel. Additional restrictions on out-of-band emissions may also apply.
Many experts believe the FCC ruling may cause the next wireless revolution. The short range wireless access in DTV-WS has been referred to as “Wi-Fi on steroids” and “Wi-Fi 2.0” in the media. Indeed, unlicensed access in DTV-WS may decrease congestion on the 2.4 GHz ISM band, and may provide improved data rates and coverage due to the propagation properties of the spectrum.